In connection with a signal transmission, a repeater is used to pick up a signal, possibly to condition it, and to transmit it again. Within the context of a mobile radio network, such a repeater is used, by way of example, to transmit a radio signal to an area which is in shadow of the radio waves, such as a building.
In this case, the repeater communicates firstly with a base station—situated outside the building—in the mobile radio network and secondly possibly with a mobile radio terminal (mobile telephone)—situated in the building. In this context, the direction of transmission from the base station to the mobile radio terminal is called the “downlink direction”, while the transmission in the opposite direction from the mobile radio terminal to the base station is called the “uplink direction”.
In the absence of uplink signals from the mobile radio terminals, WO 98/43371 A1 discloses the practice of putting a satellite repeater completely into a standby mode, that is to say of shutting it down in principle, for power-saving purposes.
In the downlink direction, a radio signal arriving at the repeater from the base station is usually always transmitted (having been amplified) in the building, regardless of whether the mobile radio terminal communicating with the base station is situated in the building or outside the building. If the relevant mobile radio terminal is situated outside the building, people who are in the building are therefore unnecessarily exposed to magnetic radiation coming from the repeater. In order to comply with demands for less electromagnetic radiation pollution (“electrosmog”), unnecessary radiation sources of this kind need to be eliminated as far as possible.
US 2008/0249214 A1, US 2008/0031174 A1, EP 1 748 576 A2, U.S. Pat. No. 4,794,649 A and EP 2 106 174 A2 disclose repeaters which can be switched to a power-saving mode with reduced radiated power.
A repeater, the operation of which involves as little electromagnetic radiation as possible being emitted is desirable. Specifying a method of operation with as little radiation as possible is also desirable.